The present invention relates to improved method for manufacturing an eyeglass-frame, and more particularly relates to an improvement in manufacturing of a metallic eyeglass-frame by casting.
A metallic eyeglass-frame generally includes a pair of rims each holding a lens, an upper and a lower bridge for connecting the rims, a pair of lugs or decorations projecting sideways from the associated rims, a pair of pads or cringles attached to the facing edges of the rims below the bridges, and a pair of bows or sides extending rearwardly from the associated lugs. The pads are made of synthetic resin and adapted to rest on the nose of the wearer in order to hold the eyeglasses in position on the wearers face. Each pad is coupled to the associated metallic rim by means of a curved, linear pad holder extending from the edge of the rim and a pad core attached to the distal end of the pad holder.
In the conventional process for manufacturing eyeglass frames, in particular the pad holder, a thin metallic wire obtained by drawing a thick metallic rod is subjected first to rolling in order to have a required cross sectional profile and dimension, and next bending the rod in order to have a configuration adapted for a pad holder which is then attached to the edge of the associated rim by brazing.
Such a conventional process includes many operational steps and the brazing operation requires highly skilled technique. In addition, since an eyeglass-frame, in particular its part around the pads are always located quite close to the wearer's face, the pads and their related parts are placed under a condition considerably subject to corrosion by sweat. As is well known, brazing material are in general very vulnerable to corrosion of this sort. Thus, development in corrosion is lialbe to cause accidental separation of the pad holder with the pad from the associated rim.
Use of silver for the brazing material may somewhat alleviate such corrosion problems but not completely. In addition, use of such an expensive brazing material naturally is costly.
Further, the use of drawing and rolling operations in the conventional process places undesirable restriction on designing of eyeglass-frames. For example, the formation of a pad holder having a varying diameter along its length necessitates highly complicated operational steps which naturally add to the cost of the glasses.